Question: Evaluate $x-(-y)$ where $x = -2.31$ and $y = 5.9$.
Explanation: Let's substitute ${x = -2.31}$ and ${y = 5.9}$ into the expression. $\begin{aligned} &\phantom{=} {x}-(-{y}) \\\\ &= {\left(-2.31\right)}-\left(-{5.9}\right) \end{aligned}$ $= -2.31+5.9$ $=3.59$